align-constraint: Follow the position of the source

The AlignConstraint update is using only the width/height of the source,
but it should also take into account the position.

Also, instead of using the ::notify signal, it should follow the
BindConstraint, and switch to the ::allocation-changed signal, since
it's less expensive (one emission instead of four notifications, one for
each property we use).

diff --git a/clutter/clutter-align-constraint.c b/clutter/clutter-align-constraint.c
index e208a2f..23de475 100644 (file)
--- a/clutter/clutter-align-constraint.c
+++ b/clutter/clutter-align-constraint.c
@@ -83,8 +83,13 @@ update_actor_position (ClutterAlignConstraint *align)
 {
   gfloat source_width, source_height;
   gfloat actor_width, actor_height;
+  gfloat source_x, source_y;
+  gfloat new_position;
   ClutterActor *actor;
 
+  if (align->source == NULL)
+    return;
+
   if (!clutter_actor_meta_get_enabled (CLUTTER_ACTOR_META (align)))
     return;
 
@@ -92,34 +97,33 @@ update_actor_position (ClutterAlignConstraint *align)
   if (actor == NULL)
     return;
 
-  if (align->source == NULL)
-    return;
-
+  clutter_actor_get_position (align->source, &source_x, &source_y);
   clutter_actor_get_size (align->source, &source_width, &source_height);
   clutter_actor_get_size (actor, &actor_width, &actor_height);
 
   switch (align->align_axis)
     {
     case CLUTTER_ALIGN_X_AXIS:
-      clutter_actor_set_x (actor, (source_width - actor_width) * align->factor);
+      new_position = ((source_width - actor_width) + source_x)
+                   * align->factor;
+      clutter_actor_set_x (actor, new_position);
       break;
 
     case CLUTTER_ALIGN_Y_AXIS:
-      clutter_actor_set_y (actor, (source_height - actor_height) * align->factor);
+      new_position = ((source_height - actor_height) + source_y)
+                   * align->factor;
+      clutter_actor_set_y (actor, new_position);
       break;
     }
 }
 
 static void
-source_position_changed (GObject                *gobject,
-                         GParamSpec             *pspec,
+source_position_changed (ClutterActor           *actor,
+                         const ClutterActorBox  *allocation,
+                         ClutterAllocationFlags  flags,
                          ClutterAlignConstraint *align)
 {
-  if (strcmp (pspec->name, "width") == 0 ||
-      strcmp (pspec->name, "height") == 0)
-    {
-      update_actor_position (align);
-    }
+  update_actor_position (align);
 }
 
 static void
@@ -320,7 +324,7 @@ clutter_align_constraint_set_source (ClutterAlignConstraint *align,
 
   if (align->source != NULL)
     {
-      g_signal_connect (align->source, "notify",
+      g_signal_connect (align->source, "allocation-changed",
                         G_CALLBACK (source_position_changed),
                         align);
       g_signal_connect (align->source, "destroy",